Cattle were first brought to North America during colonization when settlers from Spain, France, the Netherlands and Great Britain brought livestock with them. Cattle could have also been introduced from the Caribbean islands if the vessels stopped there to restock supplies. In Virginia's Jamestown Colony, historical records are incomplete as to the origin of its imported cattle. However, it is currently believed but not adequately documented that Virginia's foundation cattle herd were Devons from Devonshire, England. On the other hand, because there were so many possible cattle origins in North America, historians and other researchers alike are curious to learn more about the ancestry of Virginia's colonial cattle and the trade routes from which they came. The overall objective of this thesis research was to provide genetic evidence for the ancestry of Jamestown's colonial cattle that will clarify and supplement historical records.
To discover the origin of colonial cattle, mitochondrial DNA (mtDNA) was analyzed from ancient bone samples. Because mtDNA is maternally inherited, it is often used to determine the ancestry of populations. Samples were taken from various sites that were occupied by early Virginia settlers throughout the Jamestown region. Total DNA was extracted and a 218-bp piece of the most variable region of Bos taurus mtDNA, known as the displacement loop (D-loop), was amplified and sequenced.
Ancient DNA is difficult to sequence, especially from samples that have been degrading in fluctuating environmental conditions for the past four hundred years. From the 22 bones analyzed, high quality sequences were obtained from 5 of them. DNA from the cheek cells of two living Devon cows was also sequenced for the basis of comparison. All sample sequences obtained were compared to the published Aberdeen Angus 218-bp fragment because it is the most common cow in Europe (Accession # V00654). All five sequences from bone samples matched exactly to the comparison sequence, and one of the Devon cow samples showed this exact match as well. The other Devon cow sequence consistently showed variation from the comparison sequence at positions 99 and 126.
It has been previously shown that, despite the variability of the D-loop region, Bos taurus breeds are differentiated into haplotypes based on as little as 1-2 nucleotide changes in the DNA base sequence from the common Aberdeen Angus comparison sequence. Some individuals that belong to different Bos taurus breeds have the exact same base sequence as the Aberdeen Angus. Within each breed of cattle, individuals often display mtDNA D-loop variation that is inconsistent between other members of that breed. Therefore, because there is not as much mtDNA diversity in Bos taurus cattle as once assumed and variation is often inconsistent within breeds, the origin of colonial cattle in Virginia cannot be determined with certainty. All of the successfully sequenced samples match that of one of the Devon cows, thus there is a possibility that the foundation herd in Jamestown was indeed made up of Devon cattle. However, this Devon sample also completely matched the Aberdeen Angus sequence. Because members of other breeds like the Kerry and Cuban Creole also match the Aberdeen Angus sequence exactly, these possibilities cannot be eliminated. More sequences from both ancient and Devon cow samples need to be obtained and analyzed before conclusions can be made about the ancestry of Jamestown's colonial cattle.